As shown in FIG. 1, the conventional technique is constituted such that: a key scanning circuit 1 is not only connected to a counter 2 directly but also connected through an inverter N1; further the key scanning circuit 1 is connected to an output control circuit 3; the counter 2 to which clocks CK are supplied is connected to the output control circuit 3; and the output control circuit 3 is connected to a RAM 4.
Further as shown in FIG. 2, the data for use in the RAM 4 consists of 3 bytes, and the upper two bytes represent the information on the note length, while the lower one byte represents the note number. Here "N/R" is a bit for showing as to whether it is a note or a rest. When this bit is set as a rest, the note number data consisting of 3 bytes are not required, but the expression becomes possible by means of only two bytes. Further, the 7th bit P of the third byte is a polyphonic bit which is set upon entering of a polyphonic key input.
Referring to FIG. 1, the key information inputted from the key scanning circuit 1 is interpreted, before breaking it down into a key number data NN a key-on data No and a key-off data Nf, and the N/R bit of FIG. 2 is set by means of the key-on data No and the key-off data Nf, while the on and off times are respectively counted by means of the counter 2 based on the system clock CK. Thus, upon completion of the counting, the counted values of the counter 2 are assigned to the note length bit of FIG. 2, while, in the case of a note, it is recorded on the RAM 4 together with the note number data.
Under this condition, a polyphonic bit P is set upon a polyphonic key input, and the next key data of the pressed key continuously sets the polyphonic bit P, so that the chord input can be discriminated.
Further, the data of the note length consists of 15 bits, and therefore, an amount of data equivalent to 2.sup.. (=32,768) times the length of the system clock can be stored.
However, according to this conventional music recording method, in the case where the system clock CK is 10 [ms], and where the playing is made at the standard speed (d=120), the time interval of a quarter note is 0.5 seconds, and therefore, the recording can be made in the amount of over 600 notes of 15-bit length data for the time interval of over 300 seconds.
This is equivalent to one complete melody, and if the recording exceeds 5 minutes which is the maximum time for the notes. It is impossible to record anymore because the memory is squandered.